FIELD OF THE INVENTION
This invention relates to control circuit means for a hot water heating system and in particular to such means enabling significant reduction in energy consumption and, correspondingly, costs attributable thereto.
In the past, various types of hot water heating systems and control circuits therefor have been devised. The conventional system employs simple thermostatic means for actuating the heater element when the water falls below a predetermined temperature controlled by the thermostat setting. This may waste energy, for example, when the hot water heating system services a house where all occupants are normally away for extended periods of time as may occur during the working day, holidays, vacations, and the like. Provision has been made for manual switches to turn off the hot water heating system during vacations, but this involves manual operation and thus the inherent possibility of merely forgetting to turn off the switch. Other serious disadvantages detract from the reliability and efficacy of simple switch-type systems or for that matter, systems which in general depend upon a thermostat device as the sole or principal means for activating the water heating element. For example, malfunction of the switch, a condition which might very well go unnoticed for a time, could restore the thermostat as the sole means for water temperature control depending upon the circuitry, i.e., assuming the malfunction to isolate the switch component from an otherwise operative electric circuit involving the thermostat and heating element; should the thermostat by mistake, inadvertence etc., be set excessively high, energy waste continues unabated until such time as the proper setting is registered. The water might well undergo repeated heatings to maintain the excessive temperature by virtue of thermostatic activation of the heating element. This situation obtains even if an on-off switch be operative in the heating element circuit should it, of course, be in the "on" position. This is particularly the case in households where children or others are present who might for some reason be incompetent to precisely set the thermostat but who nevertheless have access thereto.
In view of escalating energy demands and associated costs as well as the ever present threat of curtailment of the available energy supplies through depletion or limitation imposed by ultimate suppliers, energy saving measures are a prime focus of industrial as well as governmental organizations.
Thus, a primary object of the invention is to provide control circuit means wherein the foregoing and related problems are eliminated or at least mitigated to a substantial extent.
Another object of the invention is to provide control circuit means for water heating units enabling substantial reductions in energy waste and correspondingly in operating costs.
Still another object of the invention is to provide control circuit means for heating elements wherein any requirement for switch means to isolate a thermostat device from the heating element circuit is eliminated.
Yet another object of the invention is to provide such means capable of minimizing energy losses which would otherwise result from excessively high thermostat settings.
A further object of the invention is to provide such means wherein the thermostat means is eliminated as the sole operative means for activating the heating element.
Yet a further object of the invention is to provide such means capable of economical and simple manufacture and installation.
Other objects and advantages of the invention will become more apparent hereinafter as the description proceeds.
The attainment of the foregoing objects is made possible in accordance with the invention which in its broader aspects provides in a hot water heater having a tank, a cool water inlet and a hot water outlet and heating means for heating water in said tank, the improvement comprising a control circuit. The control circuit includes a detection device for indicating water flow, thermostat means for controlling operation of said heating means to heat said water to a predetermined temperature and thereafter de-energizing said heating means. The detection device actuates said heating means upon detection of water flow with respect to said tank to again heat the water in said tank to said predetermined temperature. Holding means for a relay controlling the termostat means is also provided.